Studies of diet and obesity with liver cancer: Liver cancer is the third leading cause of cancer-related mortality worldwide. Numerous hypotheses link different aspects of the diet, e.g. alcohol, meat, fat, fruits and vegetables, coffee, fruit juice, with liver cancer. However of that list, only alcohol is an established risk factor. In addition to dietary components, there is a growing awareness of the importance of energy balance, including obesity, diabetes, and physical activity with liver cancer. We are investigating these dietary and energy balance hypotheses, taking advantage of large prospective cohort studies. In the past couple of years, we have measured Hepatitis B (HBV) and Hepatitis C (HCV) positivity in several of our studies. HBV and HCV are strong risk factors for liver cancer and so now we can take account of these possible risk factors in our analyses. We have also measured several other analytes including insulin, glucose, vitamin D, and serum iron and aim to determine the association of these analytes with cancer. We are also in the process of examining associations with specific dietary components, such as meat, fat, coffee, and fruits and vegetables. Finally, we are examining lifestyle factors such as smoking and NSAID use. SEER-Medicare. We have worked to create a nested-case control study in the SEER-Medicare database in which to examine the association of diet and obesity related exposures with cancer risk. The very large size of the SEER-Medicare database allows us to examine hypotheses which are difficult to conduct other places-- for example the association of diabetes with particular anatomic sub-sites of the colon. We have developed the database and examined an initial set of exposures including obesity, diabetes, smoking, ulcers, gastric reflux, and pernicious anemia.